ENVIRSC 1A03 Lecture Notes - Lecture 5: Relative Humidity, Dew Point, Vapor Pressure
3 Oct 2016
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Document Summary
Knowing how much water vapour is in the atmosphere tells us how much latent heat there is. Humidity: the amount of water vapour in the air. Vapour pressure: the amount of pressure asserted on the atmosphere by water vapour in an air parcel; dependant of density and temperature of the vapour; high vapour pressure = more molecules and vice versa. Evaporation: molecules escape as water vapour and increases in the air as surface water evaporates. Condensation: water vapour molecules collide with surface of water and bond with hydrogen molecules. Saturation: condensation begins and water returns to the surface; equilibrium at which molecules condense and evaporate at the same rate. Saturation specific humidity: the specific humidity of the atmosphere when it is saturated. Consequently, more infared radiation is lost resulting in more cooling. Frost point: when air reaches saturation at temperatures below freezing.
